Split Precoding and Split Prefiltering Between a Central Unit and a Distributed Unit of a Generation Node-B (GNB)

ABSTRACT

Embodiments of a Generation Node-B (gNB) and methods of communication are disclosed herein. The gNB may be configured with logical nodes including a gNB central unit (gNB-CU) and a gNB distributed unit (gNB-DU). The gNB-CU 106 may determine a first precoding matrix and a second precoding matrix for a precoding of one or more data streams for transmission on a plurality of antennas coupled to the gNB-DU. The precoding may be in accordance with a split functionality between the gNB-CU and the gNB-DU that includes: precoding by the gNB-CU with the first precoding matrix, and precoding by the gNB-DU with the second precoding matrix.

PRIORITY CLAIM

This application claims priority under 35 USC 119(e) to U.S. ProvisionalPatent Application Ser. No. 62,543,864, filed Aug. 10, 2017 [referencenumber AA2798-Z (4884.969PRV)], which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

Embodiments pertain to wireless communications. Some embodiments relateto cellular communication networks including 3GPP (Third GenerationPartnership Project) networks, 3GPP LTE (Long Term Evolution) networks,3GPP LTE-A (LTE Advanced) networks, New Radio (NR) networks, and 5Gnetworks, although the scope of the embodiments is not limited in thisrespect. Some embodiments related to disaggregated Generation Node-Bs(gNBs). Some embodiments relate to precoding, including split precodingbetween components. Some embodiments relate to prefiltering, includingsplit prefiltering between components.

BACKGROUND

Base stations and mobile devices operating in a cellular network mayexchange data. Functionality related to various protocol layers may beimplemented in a base station to support communication with mobiledevices. In an example scenario, a large number of mobile devices maycommunicate with the base station.

In another example scenario, performance targets for a mobile device,such as latency, delay and/or other, may be challenging for the basestation to meet. Accordingly, there is a general need for methods andsystems to implement communication between the base station and themobile devices in these and other scenarios.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a functional diagram of an example network in accordance withsome embodiments;

FIG. 1B is a functional diagram of another example network in accordancewith some embodiments;

FIG. 2 illustrates a block diagram of an example machine in accordancewith some embodiments;

FIG. 3 illustrates a user device in accordance with some aspects;

FIG. 4 illustrates a base station in accordance with some aspects;

FIG. 5 illustrates an exemplary communication circuitry according tosome aspects;

FIG. 6 illustrates the operation of a method of communication inaccordance with some embodiments;

FIG. 7 illustrates the operation of another method of communication inaccordance with some embodiments;

FIG. 8 illustrates the operation of another method of communication inaccordance with some embodiments;

FIG. 9 illustrates example operations in accordance with someembodiments; and

FIG. 10 illustrates additional example operations in accordance withsome embodiments.

DETAILED DESCRIPTION

The following description and the drawings sufficiently illustratespecific embodiments to enable those skilled in the art to practicethem. Other embodiments may incorporate structural, logical, electrical,process, and other changes. Portions and features of some embodimentsmay be included in, or substituted for, those of other embodiments.Embodiments set forth in the claims encompass all available equivalentsof those claims.

FIG. 1A is a functional diagram of an example network in accordance withsome embodiments. FIG. 1B is a functional diagram of another examplenetwork in accordance with some embodiments. In references herein, “FIG.1” may include FIG. 1A and FIG. 1B. In some embodiments, the network 100may be a Third Generation Partnership Project (3GPP) network. In someembodiments, the network 150 may be a 3GPP network. In a non-limitingexample, the network 150 may be a new radio (NR) network. It should benoted that embodiments are not limited to usage of 3GPP networks,however, as other networks may be used in some embodiments. As anexample, a Fifth Generation (5G) network may be used in some cases. Asanother example, a New Radio (NR) network may be used in some cases. Asanother example, a wireless local area network (WLAN) may be used insome cases. Embodiments are not limited to these example networks,however, as other networks may be used in some embodiments. In someembodiments, a network may include one or more components shown in FIG.1A. Some embodiments may not necessarily include all components shown inFIG. 1A, and some embodiments may include additional components notshown in FIG. 1A. In some embodiments, a network may include one or morecomponents shown in FIG. 1B. Some embodiments may not necessarilyinclude all components shown in FIG. 1B, and some embodiments mayinclude additional components not shown in FIG. 1B. In some embodiments,a network may include one or more components shown in FIG. 1A and one ormore components shown in FIG. 1B. In some embodiments, a network mayinclude one or more components shown in FIG. 1A, one or more componentsshown in FIG. 1B and one or more additional components.

The network 100 may comprise a radio access network (RAN) 101 and thecore network 120 (e.g., shown as an evolved packet core (EPC)) coupledtogether through an S1 interface 115. For convenience and brevity sake,only a portion of the core network 120, as well as the RAN 101, isshown. In a non-limiting example, the RAN 101 may be an evolveduniversal terrestrial radio access network (E-UTRAN). In anothernon-limiting example, the RAN 101 may include one or more components ofa New Radio (NR) network. In another non-limiting example, the RAN 101may include one or more components of an E-UTRAN and one or morecomponents of another network (including but not limited to an NRnetwork).

The core network 120 may include a mobility management entity (MME) 122,a serving gateway (serving GW) 124, and packet data network gateway (PDNGW) 126. In some embodiments, the network 100 may include (and/orsupport) one or more Evolved Node-B′s (eNBs) 104 (which may operate asbase stations) for communicating with User Equipment (UE) 102. The eNBs104 may include macro eNBs and low power (LP) eNBs, in some embodiments.

In some embodiments, the network 100 may include (and/or support) one ormore Next Generation Node-B′s (gNBs) 105. In some embodiments, one ormore eNBs 104 may be configured to operate as gNBs 105. Embodiments arenot Limited to the number of eNBs 104 shown in FIG. 1A or to the numberof gNBs 105 shown in FIG. 1A. In some embodiments, the network 100 maynot necessarily include eNBs 104. Embodiments are also not limited tothe connectivity of components shown in FIG. 1A.

It should be noted that references herein to an eNB 104 or to a gNB 105are not limiting. In some embodiments, one or more operations, methodsand/or techniques (such as those described herein) may be practiced by abase station component (and/or other component), including but notlimited to a gNB 105, an eNB 104, a serving cell, a transmit receivepoint (TRP) and/or other. In some embodiments, the base stationcomponent may be configured to operate in accordance with a New Radio(NR) protocol and/or NR standard, although the scope of embodiments isnot limited in this respect. In some embodiments, the base stationcomponent may be configured to operate in accordance with a FifthGeneration (5G) protocol and/or 5G standard, although the scope ofembodiments is not limited in this respect.

In some embodiments, the gNB 105 may include multiple components. In anon-limiting example shown in 130, the gNB 105 may comprise one or moreof: a gNB central unit (gNB-CU) 106, a gNB distributed unit (gNB-DU) 108and/or other component(s). The gNB-CU 106 and the gNB-DU 108 maycommunicate over the F1 interface 110, although the scope of embodimentsis not limited in this respect. It should be noted that the gNB-CU 106may be referred to herein as the CU 106, in some cases. In addition, thegNB-DU 108 may be referred to herein as the DU 108, in some cases.

In some embodiments, the gNB-CU 106 and the gNB-DU 108 may be part of adisaggregated gNB 105. The gNB-CU 106 and the gNB-DU 108 may beco-located, in some embodiments. The gNB-CU 106 and the gNB-DU 108 maynot necessarily be co-located, in some embodiments.

The scope of embodiments is not limited to arrangements in which thegNB-CU 106 and the gNB-DU 108 are part of a disaggregated gNB 105,however. In some embodiments, one or more of the techniques, operationsand/or methods described herein may be practiced by a gNB-CU 106 and/orgNB-DU 108 that may not necessarily be included in a disaggregated gNB105. In some embodiments, one or more of the techniques, operationsand/or methods described herein may be practiced by a gNB 105 that maynot necessarily be a disaggregated gNB 105. In some embodiments, one ormore of the techniques, operations and/or methods described herein maybe practiced by a gNB 105 that may not necessarily include the gNB-CU106 or gNB-DU 108.

References herein to communication between the gNB 105 and anothercomponent (such as the UE 102, MME 122, SGW 124 and/or other) are notlimiting. In some embodiments, such communication may be performedbetween the component (such as the UE 102, MME 122, SGW 124 and/orother) and one or more of: the gNB-CU 106 and the gNB-DU 108. Referencesherein to an operation, technique and/or method performed by the gNB 105are not limiting. In some embodiments, such an operation, techniqueand/or method may be performed by the gNB-CU 106 and/or the gNB-DU 108.

In some embodiments, one or more of the UEs 102, gNBs 105, gNB-CU 106,gNB-DU 108 and/or eNBs 104 may be configured to operate in accordancewith an NR protocol and/or NR techniques. References to a UE 102, eNB104, gNB-CU 106, gNB-DU 108 and/or gNB 105 as part of descriptionsherein are not limiting. For instance, descriptions of one or moreoperations, techniques and/or methods practiced by a gNB 105 are notlimiting. In some embodiments, one or more of those operations,techniques and/or methods may be practiced by an eNB 104 and/or otherbase station component.

In some embodiments, the UE 102 may transmit signals (data, controland/or other) to the gNB 105, and may receive signals (data, controland/or other) from the gNB 105. In some embodiments, the UE 102 maytransmit signals (data, control and/or other) to the eNB 104, and mayreceive signals (data, control and/or other) from the eNB 104. Theseembodiments will be described in more detail below. In some embodiments,the UE 102 may transmit signals to a component of a disaggregated gNB105 (such as the gNB-DU 108 and/or other). In some embodiments, the UE102 may receive signals from a component of a disaggregated gNB 105(such as the gNB-DU 108 and/or other).

The MME 122 is similar in function to the control plane of legacyServing GPRS Support Nodes (SGSN). The MME 122 manages mobility aspectsin access such as gateway selection and tracking area list management.The serving GW 124 terminates the interface toward the RAN 101, androutes data packets between the RAN 101 and the core network 120. Inaddition, it may be a local mobility anchor point for inter-eNBhandovers and also may provide an anchor for inter-3GPP mobility. Otherresponsibilities may include lawful intercept, charging, and some policyenforcement. The serving GW 124 and the MME 122 may be implemented inone physical node or separate physical nodes. The PDN GW 126 terminatesan SGi interface toward the packet data network (PDN). The PUN GW 126routes data packets between the EPC 120 and the external PDN, and may bea key node for policy enforcement and charging data collection. It mayalso provide an anchor point for mobility with non-LTE accesses. Theexternal PDN can be any kind of IP network, as well as an IP MultimediaSubsystem (IMS) domain. The PDN GW 126 and the serving GW 124 may beimplemented in one physical node or separated physical nodes.

In some embodiments, the eNBs 104 (macro and micro) terminate the airinterface protocol and may be the first point of contact for a UE 102.In some embodiments, an eNB 104 may fulfill various logical functionsfor the network 100, including but not limited to RNC (radio networkcontroller functions) such as radio bearer management, uplink anddownlink dynamic radio resource management and data packet scheduling,and mobility management.

In some embodiments, UEs 102 may be configured to communicate OrthogonalFrequency Division Multiplexing (OFDM) communication signals with an eNB104 and/or gNB 105 over a multicarrier communication channel inaccordance with an Orthogonal Frequency Division Multiple Access (OFDMA)communication technique. In some embodiments, eNBs 104 and/or gNBs 105may be configured to communicate OFDM communication signals with a UE102 over a multicarrier communication channel in accordance with anOFDMA communication technique. The OFDM signals may comprise a pluralityof orthogonal subcarriers.

The S1 interface 115 is the interface that separates the RAN 101 and theEPC 120. It may be split into two parts: the S1-U, which carries trafficdata between the eNBs 104 and the serving GW 124, and the S1-MME, whichis a signaling interface between the eNBs 104 and the MME 122. The X2interface is the interface between eNBs 104. The X2 interface comprisestwo parts, the X2-C and X2-U. The X2-C is the control plane interfacebetween the eNBs 104, while the X2-U is the user plane interface betweenthe eNBs 104.

In some embodiments, similar functionality and/or connectivity describedfor the eNB 104 may be used for the gNB 105, although the scope ofembodiments is not limited in this respect. In a non-limiting example,the S interface 115 (and/or similar interface) may be split into twoparts: the S1-U, which carries traffic data between the gNBs 105 and theserving GW 124, and the S1-MME, which is a signaling interface betweenthe gNBs 104 and the MME 122. The X2 interface (and/or similarinterface) may enable communication between eNBs 104, communicationbetween gNBs 105 and/or communication between an eNB 104 and a gNB 105.

With cellular networks, LP cells are typically used to extend coverageto indoor areas where outdoor signals do not reach well, or to addnetwork capacity in areas with very dense phone usage, such as trainstations. As used herein, the term low power (LP) eNB refers to anysuitable relatively low power eNB for implementing a narrower cell(narrower than a macro cell) such as a femtocell, a picocell, or a microcell. Femtocell eNBs are typically provided by a mobile network operatorto its residential or enterprise customers. A femtocell is typically thesize of a residential gateway or smaller and generally connects to theuser's broadband line. Once plugged in, the femtocell connects to themobile operator's mobile network and provides extra coverage in a rangeof typically 30 to 50 meters for residential femtocells. Thus, a LP eNBmight be a femtocell eNB since it is coupled through the PDN GW 126.Similarly, a picocell is a wireless communication system typicallycovering a small area, such as in-building (offices, shopping malls,train stations, etc.), or more recently in-aircraft. A picocell eNB cangenerally connect through the X2 link to another eNB such as a macro eNBthrough its base station controller (BSC) functionality. Thus, LP eNBmay be implemented with a picocell eNB since it is coupled to a macroeNB via an X2 interface. Picocell eNBs or other LP eNBs may incorporatesome or all functionality of a macro eNB. In some cases, this may bereferred to as an access point base station or enterprise femtocell. Insome embodiments, various types of gNBs 105 may be used, including butnot limited to one or more of the eNB types described above.

In some embodiments, the network 150 may include one or more componentsconfigured to operate in accordance with one or more 3GPP standards,including but not limited to an NR standard. The network 150 shown inFIG. 1B may include a next generation RAN (NG-RAN) 155, which mayinclude one or more gNBs 105. In some embodiments, the network 150 mayinclude the E-UTRAN 160, which may include one or more eNBs. The E-UTRAN160 may be similar to the RAN 101 described herein, although the scopeof embodiments is not limited in this respect.

In some embodiments, the network 150 may include the MME 165. The MME165 may be similar to the MME 122 described herein, although the scopeof embodiments is not limited in this respect. The MME 165 may performone or more operations or functionality similar to those describedherein regarding the MME 122, although the scope of embodiments is notlimited in this respect.

In some embodiments, the network 150 may include the SGW 170. The SGW170 may be similar to the SGW 124 described herein, although the scopeof embodiments is not limited in this respect. The SGW 170 may performone or more operations or functionality similar to those describedherein regarding the SGW 124, although the scope of embodiments is notlimited in this respect.

In some embodiments, the network 150 may include component(s) and/ormodule(s) for functionality for a user plane function (UPF) and userplane functionality for PGW (PGW-U), as indicated by 175. In someembodiments, the network 150 may include component(s) and/or module(s)for functionality for a session management function (SMF) and controlplane functionality for PGW (PGW-C), as indicated by 180. In someembodiments, the component(s) and/or module(s) indicated by 175 and/or180 may be similar to the PGW 126 described herein, although the scopeof embodiments is not limited in this respect. The component(s) and/ormodule(s) indicated by 175 and/or 180 may perform one or more operationsor functionality similar to those described herein regarding the PGW126, although the scope of embodiments is not limited in this respect.One or both of the, components 170, 172 may perform at least a portionof the functionality described herein for the PGW 126, although thescope of embodiments is not limited in this respect.

Embodiments are not limited to the number or type of components shown inFIG. 1B. Embodiments are also not limited to the connectivity ofcomponents shown in FIG. 1B.

In some embodiments, a downlink resource grid may be used for downlinktransmissions from an eNB 104 to a UE 102, while uplink transmissionfrom the UE 102 to the eNB 104 may utilize similar techniques. In someembodiments, a downlink resource grid may be used for downlinktransmissions from a gNB 105 to a UE 102, while uplink transmission fromthe UE 102 to the gNB 105 may utilize similar techniques. The grid maybe a time-frequency grid, called a resource grid or time-frequencyresource grid, which is the physical resource in the downlink in eachslot. Such a time-frequency plane representation is a common practicefor OFDM systems, which makes it intuitive for radio resourceallocation. Each column and each row of the resource grid correspond toone OFDM symbol and one OFDM subcarrier, respectively. The duration ofthe resource grid in the time domain corresponds to one slot in a radioframe. The smallest time-frequency unit in a resource grid is denoted asa resource element (RE). There are several different physical downlinkchannels that are conveyed using such resource blocks. With particularrelevance to this disclosure, two of these physical downlink channelsare the physical downlink shared channel and the physical down linkcontrol channel.

As used herein, the term “circuitry” may refer to, be part of, orinclude an Application Specific Integrated Circuit (ASIC), an electroniccircuit, a processor (shared, dedicated, or group), and/or memory(shared, dedicated, or group) that execute one or more software orfirmware programs, a combinational logic circuit, and/or other suitablehardware components that provide the described functionality. In someembodiments, the circuitry may be implemented in, or functionsassociated with the circuitry may be implemented by, one or moresoftware or firmware modules. In some embodiments, circuitry may includelogic, at least partially operable in hardware. Embodiments describedherein may be implemented into a system using any suitably configuredhardware and/or software.

FIG. 2 illustrates a block diagram of an example machine in accordancewith some embodiments. The machine 200 is an example machine upon whichany one or more of the techniques and/or methodologies discussed hereinmay be performed. In alternative embodiments, the machine 200 mayoperate as a standalone device or may be connected (e.g., networked) toother machines. In a networked deployment, the machine 200 may operatein the capacity of a server machine, a client machine, or both inserver-client network environments. In an example, the machine 200 mayact as a peer machine in peer-to-peer (P2P) (or other distributed)network environment. The machine 200 may be a UE 102, eNB 104, gNB 105,gNB-CU 106, gNB-DU 108, access point (AP), station (STA), user, device,mobile device, base station, personal computer (PC), a tablet PC, aset-top box (STB), a personal digital assistant (PDA), a mobiletelephone, a smart phone, a web appliance, a network router, switch orbridge, or any machine capable of executing instructions (sequential orotherwise) that specify actions to be taken by that machine. Further,while only a single machine is illustrated, the term “machine” shallalso be taken to include any collection of machines that individually orjointly execute a set (or multiple sets) of instructions to perform anyone or more of the methodologies discussed herein, such as cloudcomputing, software as a service (SaaS), other computer clusterconfigurations.

Examples as described herein, may include, or may operate on, logic or anumber of components, modules, or mechanisms. Modules are tangibleentities (e.g., hardware) capable of performing specified operations andmay be configured or arranged in a certain manner. In an example,circuits may be arranged (e.g., internally or with respect to externalentities such as other circuits) in a specified manner as a module. Inan example, the whole or part of one or more computer systems (e.g., astandalone, client or server computer system) or one or more hardwareprocessors may be configured by firmware or software (e.g.,instructions, an application portion, or an application) as a modulethat operates to perform specified operations. In an example, thesoftware may reside on a machine readable medium. In an example, thesoftware, when executed by the underlying hardware of the module, causesthe hardware to perform the specified operations.

Accordingly, the term “module” is understood to encompass a tangibleentity, be that an entity that is physically constructed, specificallyconfigured (e.g., hardwired), or temporarily (e.g., transitorily)configured (e.g., programmed) to operate in a specified manner or toperform pan or all of any operation described herein. Consideringexamples in which modules are temporarily configured, each of themodules need not be instantiated at any one moment in time. For example,where the modules comprise a general-purpose hardware processorconfigured using software, the general-purpose hardware processor may beconfigured as respective different nodules at different times. Softwaremay accordingly configure a hardware processor, for example, toconstitute a particular module at one instance of time and to constitutea different module at a different instance of time.

The machine (e.g., computer system) 200 may include a hardware processor202 (e.g., a central processing unit (CPU), a graphics processing unit(GPU), a hardware processor core, or any combination thereof), a mainmemory 204 and a static memory 206, some or all of which may communicatewith each other via an interlink (e.g., bus) 208. The machine 200 mayfurther include a display unit 210, an alphanumeric input device 212(e.g., a keyboard), and a user interface (UI) navigation device 214(e.g., a mouse). In an example, the display unit 210, input device 212and UI navigation device 214 may be a touch screen display. The machine200 may additionally include a storage device (e.g., drive unit) 216, asignal generation device 218 (e.g., a speaker), a network interfacedevice 220, and one or more sensors 221, such as a global positioningsystem (GPS) sensor, compass, accelerometer, or other sensor. Themachine 200 may include an output controller 228, such as a serial(e.g., universal serial bus (USB), parallel, or other wired or wireless(e.g., infrared (IR), near field communication (NFC), etc.) connectionto communicate or control one or more peripheral devices (e.g., aprinter, card reader, etc.).

The storage device 216 may include a machine readable medium 222 onwhich is stored one or more sets of data structures or instructions 224(e.g., software) embodying or utilized by any one or more of thetechniques or functions described herein. The instructions 224 may alsoreside, completely or at least partially, within the main memory 204,within static memory 206, or within the hardware processor 202 duringexecution thereof by the machine 200. In an example, one or anycombination of the hardware processor 202, the main memory 204, thestatic memory 206, or the storage device 216 may constitute machinereadable media. In some embodiments, the machine readable medium may beor may include a non-transitory computer-readable storage medium. Insome embodiments, the machine readable medium may be or may include acomputer-readable storage medium.

While the machine readable medium 222 is illustrated as a single medium,the term “machine readable medium” may include a single medium ormultiple media (e.g., a centralized or distributed database, and/orassociated caches and servers) configured to store the one or moreinstructions 224. The term “machine readable medium” may include anymedium that is capable of storing, encoding, or carrying instructionsfor execution by the machine 200 and that cause the machine 200 toperform any one or more of the techniques of the present disclosure, orthat is capable of storing, encoding or carrying data structures used byor associated with such instructions. Non-limiting machine readablemedium examples may include solid-state memories, and optical andmagnetic media. Specific examples of machine readable media may include:non-volatile memory, such as semiconductor memory devices ElectricallyProgrammable Read-Only Memory (EPROM), Electrically ErasableProgrammable Read-Only Memory, (EEPROM)) and flash memory devices;magnetic disks, such as internal hard disks and removable disks;magneto-optical disks; Random Access Memory (RAM); and CD-ROM andDVD-ROM disks. In some examples, machine readable media may includenon-transitory machine readable media. In some examples, machinereadable media may include machine readable media that is not atransitory propagating signal.

The instructions 224 may further be transmitted or received over acommunications network 226 using a transmission medium via the networkinterface device 220 utilizing any one of a number of transfer protocols(e.g., frame relay, internet protocol (LP), transmission controlprotocol (TCP), user datagram protocol (UDP), hypertext transferprotocol (HTTP), etc.). Example communication networks may include alocal area network (LAN), a wide area network (WAN), a packet datanetwork (e.g., the Internet), mobile telephone networks (e.g., cellularnetworks), Plain Old Telephone (POTS) networks, and wireless datanetworks (e.g., Institute of Electrical and Electronics Engineers (IEEE)802.11 family of standards known as Wi-Fi®, IEEE 802.16 family ofstandards known as WiMax®), IEEE 802.15.4 family of standards, a LongTerm Evolution (LTE) family of standards, a Universal MobileTelecommunications System (UMTS) family of standards, peer-to-peer (P2P)networks, among others. In an example, the network interface device 220may include one or more physical jacks (e.g., Ethernet, coaxial, orphone jacks) or one or more antennas to connect to the communicationsnetwork 226. In an example, the network interface device 220 may includea plurality of antennas to wirelessly communicate using at least one ofsingle-input multiple-output (SIMO), multiple-input multiple-output(MIMO), or multiple-input single-output (MISO) techniques. In someexamples, the network interface device 220 may wirelessly communicateusing Multiple User MIMO techniques. The term “transmission medium”shall be taken to include any intangible medium that is capable ofstoring, encoding or carrying instructions for execution by the machine200, and includes digital or analog communications signals or otherintangible medium to facilitate communication of such software.

FIG. 3 illustrates a user device in accordance with some aspects. Insome embodiments, the user device 300 may be a mobile device. In someembodiments, the user device 300 may be or may be configured to operateas a User Equipment (UE). In some embodiments, the user device 300 maybe arranged to operate in accordance with a new radio (NR) protocol. Insome embodiments, the user device 300 may be arranged to operate inaccordance with a Third Generation Partnership Protocol (3GPP) protocol.The user device 300 may be suitable for use as a UE 102 as depicted inFIG. 1, in some embodiments. It should be rioted that in someembodiments, a UE, an apparatus of a UE, a user device or an apparatusof a user device may include one or more of the components shown in oneor more of FIGS. 2, 3, and 5. In some embodiments, such a UE, userdevice and/or apparatus may include one or more additional components.

In some aspects, the user device 300 may include an applicationprocessor 305, baseband processor 310 (also referred to as a basebandmodule), radio front end module (RFEM) 315, memory 320, connectivitymodule 325, near field communication (NFC) controller 330, audio driver335, camera driver 340, touch screen 345, display driver 350, sensors355, removable memory 360, power management integrated circuit (PMIC)365 and smart battery 370. In some aspects, the user device 300 may be aUser Equipment (UE).

In some aspects, application processor 305 may include, for example, oneor more CPU cores and one or more of cache memory, low drop-out voltageregulators (LDOs), interrupt controllers, serial interfaces such asserial peripheral interface (SPI), inter-integrated circuit (I²C) oruniversal programmable serial interface module, real time clock (RTC),timer-counters including interval and watchdog timers, general purposeinput-output (IO), memory card controllers such as securedigital/multi-media card (SD/MMC) or similar, universal serial bus (USB)interfaces, mobile industry processor interface (MIPI) interfaces andJoint Test Access Group (JTAG) test access ports.

In some aspects, baseband module 310 may be implemented, for example, asa solder-down substrate including one or more integrated circuits, asingle packaged integrated circuit soldered to a main circuit board,and/or a multi-chip module containing two or more integrated circuits.

FIG. 4 illustrates a base station in accordance with some aspects. Insome embodiments, the base station 400 may be or may be configured tooperate as an Evolved Node-B (eNB). In some embodiments, the basestation 400 may be or may be configured to operate as a Next GenerationNode-B (gNB). In some embodiments, the base station 400 may be arrangedto operate in accordance with a new radio (NR) protocol. In someembodiments, the base station 400 may be arranged to operate inaccordance with a Third Generation Partnership Protocol (3GPP) protocol.It should be noted that in some embodiments, the base station 400 may bea stationary non-mobile device. The base station 400 may be suitable foruse as an eNB 104 as depicted in FIG. 1, in some embodiments. The basestation 400 may be suitable for use as a gNB 105 as depicted in FIG. 1,in some embodiments. It should be noted that in some embodiments, aneNB, an apparatus of an eNB, a gNB, an apparatus of a gNB, a gNB-CU 106,an apparatus of a gNB-CU 106, a gNB-DU 108, an apparatus of a gNB-DU108, a base station and/or an apparatus of a base station may includeone or more of the components shown in one or more of FIGS. 2, 4, and 5.In some embodiments, such an eNB, gNB, gNB-CU, a gNB-DU, base stationand/or apparatus may include one or more additional components.

FIG. 4 illustrates a base station or infrastructure equipment radio head400 in accordance with some aspects. The base station 400 may includeone or more of application processor 405, baseband modules 410, one ormore radio front end modules 415, memory 420, power management circuitry425, power tee circuitry 430, network controller 435, network interfaceconnector 440, satellite navigation receiver module 445, and userinterface 450. In some aspects, the base station 400 may be an EvolvedNode-B (eNB), which may be arranged to operate in accordance with a 3GPPprotocol, new radio (NR) protocol and/or Fifth Generation (5G) protocol.In some aspects, the base station 400 may be a Next Generation Node-B(gNB), which may be arranged to operate in accordance with a 3GPPprotocol, new radio (NR) protocol and/or Fifth Generation (5G) protocol.

In some aspects, application processor 405 may include one or more CPUcores and one or more of cache memory, low drop-out voltage regulators(LDOs), interrupt controllers, serial interfaces such as SPI, I²C oruniversal programmable serial interface module, real time clock (RTC),tinier-counters including interval and watchdog timers, general purposeIO, memory card controllers such as SD/MMC or similar, USB interfaces,MIPI interfaces and Joint Test Access Group (JTAG) test access ports.

In some aspects, baseband processor 410 may be implemented, for example,as a solder-down substrate including one or more integrated circuits, asingle packaged integrated circuit soldered to a main circuit board or amulti-chip module containing two or more integrated circuits.

In some aspects, memory 420 may include one or more of volatile memoryincluding dynamic random access memory (DRAM) and/or synchronous dynamicrandom access memory (SDRAM), and nonvolatile memory (NVM) includinghigh-speed electrically erasable memory (commonly referred to as Flashmemory), phase change random access memory (PRAM), magneto-resistiverandom access memory (MRAM) and/or a three-dimensional cross-pointmemory. Memory 420 may be implemented as one or more of solder downpackaged integrated circuits, socketed memory modules and plug-in memorycards.

In some aspects, power management integrated circuitry 425 may includeone or more of voltage regulators, surge protectors, power alarmdetection circuitry and one or more backup power sources such as abattery or capacitor. Power alarm detection circuitry may detect one ormore of brown out (under-voltage) and surge (over-voltage) conditions.

In some aspects, power tee circuitry 430 may provide for electricalpower drawn from a network cable to provide both power supply and dataconnectivity to the base station 400 using a single cable. In someaspects, network controller 435 may provide connectivity to a networkusing a standard network interface protocol such as Ethernet. Networkconnectivity may be provided using a physical connection which is one ofelectrical (commonly referred to as copper interconnect), optical orwireless.

In some aspects, satellite navigation receiver module 445 may includecircuitry to receive and decode signals transmitted by one or morenavigation satellite constellations such as the global positioningsystem (GPS), Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS),Galileo and/or BeiDou. The receiver 445 may provide data to applicationprocessor 405 which may include one or more of position data or timedata. Application processor 405 may use time data to synchronizeoperations with other radio base stations. In some aspects, userinterface 450 may include one or more of physical or virtual buttons,such as a reset button, one or more indicators such as light emittingdiodes (LEDs) and a display screen.

FIG. 5 illustrates an exemplary communication circuitry according tosome aspects. Circuitry 500 is alternatively grouped according tofunctions. Components as shown in 500 are shown here for illustrativepurposes and may include other components not shown here in FIG. 5. Insome aspects, the communication circuitry 500 may be used for millimeterwave communication, although aspects are not limited to millimeter wavecommunication. Communication at any suitable frequency may be performedby the communication circuitry 500 in some aspects.

It should be noted that a device, such as a UE 102, eNB 104, gNB 105,gNB-CU 106, gNB-DU 108, the user device 300, the base station 400, themachine 200 and/or other device may include one or more components ofthe communication circuitry 500, in some aspects.

The communication circuitry 500 may include protocol processingcircuitry 505, which may implement one or more of medium access control(MAC), radio link control (RLC), packet data convergence protocol(PDCP), radio resource control (RRC) and non-access stratum (NAS)functions. Protocol processing circuitry 505 may include one or moreprocessing cores (not shown) to execute instructions and one or morememory structures (not shown) to store program and data information.

The communication circuitry 500 may further include digital basebandcircuitry 510, which may implement physical layer (PHY) functionsincluding one or more of hybrid automatic repeat request (HARQ)functions, scrambling and/or descrambling, coding and/or decoding, layermapping and/or de-mapping, modulation symbol mapping, received symboland/or bit metric determination, multi-antenna port pre-coding and/ordecoding which may include one or more of space-time, space-frequency orspatial coding, reference signal generation and/or detection, preamblesequence generation and/or decoding, synchronization sequence generationand/or detection, control channel signal blind decoding, and otherrelated functions.

The communication circuitry 500 may further include transmit circuitry515, receive circuitry 520 and/or antenna array circuitry 530. Thecommunication circuitry 500 may further include radio frequency (RF)circuitry 525. In an aspect of the disclosure, RF circuitry 525 mayinclude multiple parallel RF chains for one or more of transmit orreceive functions, each connected to one or more antennas of the antennaarray 530.

In an aspect of the disclosure, protocol processing circuitry 505 mayinclude one or more instances of control circuitry (not shown) toprovide control functions for one or more of digital baseband circuitry510, transmit circuitry 515, receive circuitry 520, and/or radiofrequency circuitry 525.

In some embodiments, processing circuitry may perform one or moreoperations described herein and/or other operation(s). In a non-limitingexample, the processing circuitry may include one or more componentssuch as the processor 202, application processor 305, baseband module310, application processor 405, baseband module 410, protocol processingcircuitry 505, digital baseband circuitry 510, similar component(s)and/or other component(s).

In some embodiments, a transceiver may transmit one or more elements(including but not limited to those described herein) and/or receive oneor more elements (including but not limited to those described herein).In a non-limiting example, the transceiver may include one or morecomponents such as the radio front end module 315, radio front endmodule 415, transmit circuitry 515, receive circuitry 520, radiofrequency circuitry 525, similar component(s) and/or other component(s).

One or more antennas (such as 230, 312, 412, 530 and/or others) maycomprise one or more directional or omnidirectional antennas, including,for example, dipole antennas, monopole antennas, patch antennas, loopantennas, microstrip antennas or other types of antennas suitable fortransmission of RF signals. In some multiple-input multiple-output(MIMO) embodiments, one or more of the antennas (such as 230, 312, 412,530 and/or others) may be effectively separated to take advantage ofspatial diversity and the different channel characteristics that mayresult.

In some embodiments, the UE 102, eNB 104, gNB 105, gNB-CU 106, gNB-DU108, user device 300, base station 400, machine 200 and/or other devicedescribed herein may be a mobile device and/or portable wirelesscommunication device, such as a personal digital assistant (PDA), alaptop or portable computer with wireless communication capability, aweb tablet, a wireless telephone, a smartphone, a wireless headset, apager, an instant messaging device, a digital camera, an access point, atelevision, a wearable device such as a medical device (e.g., a heartrate monitor, a blood pressure monitor, etc.), or other device that mayreceive and/or transmit information wirelessly. In some embodiments, theUE 102, eNB 104, gNB 105, gNB-CU 106, gNB-DU 108, user device 300, basestation 400, machine 200 and/or other device described herein may beconfigured to operate in accordance with 3GPP standards, although thescope of the embodiments is not limited in this respect. In someembodiments, the UE 102, eNB 104, gNB 105, gNB-CU 106, gNB-DU 108, userdevice 300, base station 400, machine 200 and/or other device describedherein may be configured to operate in accordance with new radio (NR)standards, although the scope of the embodiments is not limited in thisrespect. In some embodiments, the UE 102, eNB 104, gNB 105, gNB-CU 106,gNB-DU 108, user device 300, base station 400, machine 200 and/or otherdevice described herein may be configured to operate according to otherprotocols or standards, including IEEE 802.11 or other IEEE standards.In some embodiments, the UE 102, eNB 104, gNB 105, gNB-CU 106, gNB-DU108, user device 300, base station 400, machine 200 and/or other devicedescribed herein may include one or more of a keyboard, a display, anon-volatile memory port, multiple antennas, a graphics processor, anapplication processor, speakers, and other mobile device elements. Thedisplay may be an LCD screen including a touch screen.

Although the UE 102, eNB 104, gNB 105, gNB-CU 106, gNB-DU 108, userdevice 300, base station 400, machine 200 and/or other device describedherein may each be illustrated as having several separate functionalelements, one or more of the functional elements may be combined and maybe implemented by combinations of software-configured elements, such asprocessing elements including digital signal processors (DSPs), and/orother hardware elements. For example, some elements may comprise one ormore microprocessors, DSPs, field-programmable gate arrays (FPGAs),application specific integrated circuits (ASICs), radio-frequencyintegrated circuits (RFICs) and combinations of various hardware andlogic circuitry for performing at least the functions described herein.In some embodiments, the functional elements may refer to one or moreprocesses operating on one or more processing elements.

Embodiments may be implemented in one or a combination of hardware,firmware and software. Embodiments may also be implemented asinstructions stored on a computer-readable storage device, which may beread and executed by at least one processor to perform the operationsdescribed herein. A computer-readable storage device may include anynon-transitory mechanism for storing information in a form readable by amachine (e.g., a computer). For example, a computer-readable storagedevice may include read-only memory (ROM), random-access memory (RAM),magnetic disk storage media, optical storage media, flash-memorydevices, and other storage devices and media. Some embodiments mayinclude one or more processors and may be configured with instructionsstored on a computer-readable storage device.

It should be noted that in some embodiments, an apparatus of the UE 102,eNB 104, gNB 105, gNB-CU 106, gNB-DU 108, machine 200, user device 300and/or base station 400 may include various components shown in FIGS.2-5. Accordingly, techniques and operations described herein that referto the UE 102 may be applicable to an apparatus of a UE. In addition,techniques and operations described herein that refer to the eNB 104 maybe applicable to an apparatus of an eNB. In addition, techniques andoperations described herein that refer to the gNB 105 may be applicableto an apparatus of a gNB. In addition, techniques and operationsdescribed herein that refer to the gNB-CU 106, may be applicable to anapparatus of a gNB-CU. In addition, techniques and operations describedherein that refer to the gNB-DU 108 may be applicable to an apparatus ofa gNB-DU,

It should be noted that some of the descriptions herein may refer toperformance of operations, methods and/or techniques by components suchas the gNB 105, the gNB-CU 106, and the gNB-DU 108. Such references arenot limiting, however. For instance, descriptions herein may refer toperformance of an operation by one of those components. In someembodiments, one of the other components may perform the same operation,a similar operation, a related operation and/or a reciprocal operation.In a non-limiting example, the gNB-CU 106 may perform an operation (suchas transmission of a packet), and the gNB-DU 108 may perform areciprocal operation (such as reception of the packet). In anon-limiting example, the gNB-DU 108 may perform an operation (such astransmission of a packet), and the UE 102 may perform a reciprocaloperation (such as reception of the packet).

In accordance with some embodiments, a generation node B (gNB) 105 maybe configured with logical nodes including a gNB central unit (gNB-CU)106 and a gNB distributed unit (gNB-DU) 108. The gNB-CU 106 may beconfigured to communicate with the gNB-DU 108 over an F1 interface. ThegNB 105 may determine, by the gNB-CU 106, a first precoding matrix and asecond precoding matrix for a precoding of one or more data streams fortransmission on a plurality of antennas coupled to the gNB-DU 108. Theprecoding may be in accordance with a split functionality between thegNB-CU 106 and the gNB-DU 108 that includes: precoding by the gNB-CU 106with the first precoding matrix, and precoding by the gNB-DU 108 withthe second precoding matrix. The gNB-CU 106 may be configured to precodefirst symbols from the data streams by the first precoding matrix togenerate second symbols for transfer on the F1 interface to the gNB-DU108. The gNB-DU 108 may be configured to precode the second symbols bythe second precoding matrix to generate third symbols for transmissionon the antennas. These embodiments are described in more detail below.

FIG. 6 illustrates the operation of a method of communication inaccordance with some embodiments. FIG. 7 illustrates the operation ofanother method of communication in accordance with some embodiments.FIG. 8 illustrates the operation of another method of communication inaccordance with some embodiments. It is important to note thatembodiments of the methods 600, 700, 800 may include additional or evenfewer operations or processes in comparison to what is illustrated inFIGS. 6-8. In addition, embodiments of the methods 600, 700, 800 are notnecessarily limited to the chronological order that is shown in FIGS.6-8. In describing the methods 600, 700, 800, reference may be made toone or more figures, although it is understood that the methods 600,700, 800 may be practiced with any other suitable systems, interfacesand components.

In some embodiments, a gNB-CU 106 may perform one or more operations ofthe method 600, but embodiments are not limited to performance of themethod 600 and/or operations of it by the gNB-CU 106. In someembodiments, another device and/or component may perform one or moreoperations of the method 600. In some embodiments, another device and/orcomponent may perform one or more operations that may be similar to oneor more operations of the method 600. In some embodiments, anotherdevice and/or component may perform one or more operations that may bereciprocal to one or more operations of the method 600. In anon-limiting example, the gNB 105 may perform an operation that may bethe same as, similar to, reciprocal to and/or related to an operation ofthe method 600, in some embodiments.

In some embodiments, a gNB-DU 108 may perform one or more operations ofthe method 700, but embodiments are not limited to performance of themethod 700 and/or operations of it by the gNB-DU 108. In someembodiments, another device and/or component may perform one or moreoperations of the method 700. In some embodiments, another device and/orcomponent may perform one or more operations that may be similar to oneor more operations of the method 700. In some embodiments, anotherdevice and/or component may perform one or more operations that may bereciprocal to one or more operations of the method 700. In anon-limiting example, the gNB 105 may perform an operation that may bethe same as, similar to, reciprocal to and/or related to an operation ofthe method 700, in some embodiments.

In some embodiments, a UE 102 may perform one or more operations of themethod 800, but embodiments are not limited to performance of the method800 and/or operations of it by the UE 102. In some embodiments, anotherdevice and/or component may perform one or more operations of the method800. In some embodiments, another device and/or component may performone or more operations that may be similar to one or more operations ofthe method 800. In some embodiments, another device and/or component mayperform one or more operations that may be reciprocal to one or moreoperations of the method 800.

It should be noted that one or more operations of one of the methods600, 700, 800 may be the same as, similar to and/or reciprocal to one ormore operations of the other methods. For instance, an operation of themethod 600 may be the same as, similar to and/or reciprocal to anoperation of the method 700, in some embodiments. In a non-limitingexample, an operation of the method 600 may include transmission of anelement (such as a frame, block, message and/or other) by the gNB-CU106, and an operation of the method 700 may include reception of a sameelement (and/or similar element) by the gNB-DU 108 from the gNB-CU 106.In some cases, descriptions of operations and techniques described aspart of one of the methods 600, 700, 800 may be relevant to one or bothof the other methods.

Discussion of various techniques and concepts regarding one of themethods 600, 700, 800 and/or other method may be applicable to one ofthe other methods, although the scope of embodiments is not limited inthis respect. Such technique and concepts may include precoding,precoding matrixes, precoding matrix packet, prefiltering, prefilteringmatrixes, prefiltering matrix packet, transfer on the F1 interfaceand/or other.

The methods 600, 700, 800 and other methods described herein may referto eNBs 104, gNBs 105, gNB-CUs 106, gNB-DUs 108 and/or UEs 102 operatingin accordance with 3GPP standards, 5G standards, NR standards and/orother standards. However, embodiments are not limited to performance ofthose methods by those components, and may also be performed by otherdevices, such as a Wi-Fi access point (AP) or user station (STA). Inaddition, the methods 600, 700, 800 and other methods described hereinmay be practiced by wireless devices configured to operate in othersuitable types of wireless communication systems, including systemsconfigured to operate according to various IEEE standards such as IEEE802.11. The methods 600, 700, 800 may also be applicable to an apparatusof a UE 102, an apparatus of an eNB 104, an apparatus of a gNB 105, anapparatus of a gNB-CU 106, an apparatus of a gNB-DU 108 and/or anapparatus of another device described above.

It should also be noted that embodiments are not limited by referencesherein (such as in descriptions of the methods 600, 700 and 800 and/orother descriptions herein) to transmission, reception and/or exchangingof elements such as frames, messages, requests, indicators, signals orother elements. In some embodiments, such an element may be generated,encoded or otherwise processed by processing circuitry (such as by abaseband processor included in the processing circuitry) fortransmission. The transmission may be performed by a transceiver orother component, in some cases. In some embodiments, such an element maybe decoded, detected or otherwise processed by the processing circuitry(such as by the baseband processor). The element may be received by atransceiver or other component, in some cases. In some embodiments, theprocessing circuitry and the transceiver may be included in a sameapparatus. The scope of embodiments is not limited in this respect,however, as the transceiver may be separate from the apparatus thatcomprises the processing circuitry, in some embodiments.

One or more of the elements (such as messages, operations and/or other)described herein may be included in a standard and/or protocol,including but not limited to Third Generation Partnership Project(3GPP), 3GPP Long Term Evolution (LTE), Fourth Generation (4G), FifthGeneration (5G), New Radio (NR) and/or other. The scope of embodimentsis not limited to usage of elements that are included in standards,however.

In some embodiments, the gNB 105 may be configured with logical nodesincluding a gNB central unit (gNB-CU) 106 and a gNB distributed unit(gNB-DU) 108, and the gNB-CU 106 and the gNB-DU 108 may be configured tocommunicate with each other over an F1 interface. The scope ofembodiments is not limited in this respect, however, as another device(such as a gNB 105 that does not necessarily include the gNB-CU 106 andgNB-DU 108) may perform one or more operations of the method 600 and/orother operations described herein.

At operation 605, the gNB-CU 106 may receive information related to oneor more signal quality measurements. In some embodiments, theinformation related to the signal quality measurements may be receivedfrom the gNB-DU 108, although the scope of embodiments is not limited inthis respect. In some embodiments, the signal quality measurements maybe determined at the UE 102. In some embodiments, the UE 102 maytransmit information related to the signal quality measurements to thegNB-DU 108, and the gNB-DU 108 may transfer information (the informationreceived from the UE 102, a portion of the information received from theUE 102, information based on the information received from the UE 102and/or other) to the gNB-CU 106.

Example signal quality measurements (for operation 605 and/or otheroperations described herein) include, but are not limited to, receivedsignal power, average received signal power, signal-to-noise ratio(SNR), reference signal received power (RSRP), reference signal receivedquality (RSRQ), and received signal strength indicator (RSSI).

At operation 610, the gNB-CU 106 may determine a number of virtualantenna ports. At operation 615, the gNB-CU 106 may determine a firstprecoding matrix for downlink precoding. At operation 620, the gNB-CU106 may determine a second precoding matrix for the downlink precoding.

In some embodiments, the gNB-CU 106 may determine the first precodingmatrix and the second precoding matrix for a precoding of one or moredata streams for transmission on a plurality of antennas coupled to thegNB-DU 108. In some embodiments, the precoding may be in accordance witha split functionality between the gNB-CU 106 and the gNB-DU 108 thatincludes: precoding by the gNB-CU 106 with the first precoding matrix,and precoding by the gNB-DU 108 with the second precoding matrix.

In some embodiments, a number of rows of the first precoding matrix maybe equal to a number of virtual ports, a number of columns of the firstprecoding matrix may be equal to a number of the data streams, a numberof rows of the second precoding matrix may be equal to a number of theantennas coupled to the gNB-DU, and a number of columns of the secondprecoding matrix may be equal to the number of virtual ports.

In some embodiments, the gNB-CU 106 may determine the number of virtualports as a number that is less than the number of antennas coupled tothe gNB-DU 106. In some embodiments, the gNB-CU 106 may determine thenumber of virtual ports as described above to cause a size of symbolstransferred on the F1 interface from the gNB-CU 106 to the gNB-DU 108(or from the gNB-DU 108 to the gNB-CU 106) to be less than symbolsgenerated, by the gNB-DU 108, for transmission on the antennas.

In some embodiments, the gNB-CU 106 may determine the first precodingmatrix and/or the second precoding matrix based at least partly on theone or more signal quality measurements. In some embodiments, the gNB-CU16 may perform one or more of: select the first precoding matrix fromfirst candidate precoding matrixes; and select the second precodingmatrix from second candidate precoding matrixes.

At operation 625, the gNB-CU 106 may transfer, to the gNB-DU 108,information related to the downlink precoding. In some embodiments, thegNB-CU 106 may transfer a precoding matrix packet to the gNB-DU 108. Theprecoding matrix packet may include one or more of: a number of virtualantenna ports; information related to the second precoding matrix (suchas coefficients, size of the matrix and/or other); information relatedto the first precoding matrix; and/or other information. In someembodiments, the gNB-CU 106 may encode the precoding matrix packet fortransfer to the gNB-DU 108 on the F1 interface, and the precoding matrixpacket may indicate the second precoding matrix and/or informationrelated to the precoding.

Embodiments are not limited to usage of the precoding matrix packet inthis operation and/or other operations, as other elements may be used,in some embodiments. The precoding matrix packet may be included in a3GPP protocol, 5G protocol and/or NR protocol, in some embodiments.Embodiments are not limited to usage of elements from those protocols.

At operation 630, the gNB-CU 106 may determine a prefiltering matrix foruplink prefiltering. In some embodiments, the prefiltering matrix may befor conversion of first uplink symbols received by the gNB-DU 108 from aUE 102 at the gNB-DU 108 to second uplink symbols for transfor to thegNB-CU 106 on the F1 interface, although the scope of embodiments is notlimited in this respect. In some embodiments, the gNB-DU 108 maydetermine the prefiltering matrix. Accordingly, the gNB-CU 106 may notnecessarily perform operation 630, in some embodiments.

In some embodiments, the gNB-CU 106 may determine the prefilteringmatrix based at least partly on one or more signal quality measurements.In a non-limiting example, the signal quality measurements (and/orrelated information) may be received by the gNB-CU 106 from the gNB-DU108. The signal quality measurements may be determined at the UE 102 andtransmitted to the gNB-DU 108.

At operation 635, the gNB-CU 106 may transfer, to the gNB-DU 108,information related to the uplink prefiltering. In some embodiments, thegNB-CU 106 may transfer a prefiltering matrix packet to the gNB-DU 108.The prefiltering matrix packet may include one or more of: a number ofvirtual antenna ports; information related to the prefiltering matrix(such as coefficients, size of the matrix and/or other); and/or otherinformation. Embodiments are not limited to usage of the prefilteringmatrix packet in this operation and/or other operations, as otherelements may be used, in some embodiments. The prefiltering matrixpacket may be included in a 3GPP protocol, 5G protocol and/or NRprotocol, in some embodiments. Embodiments are not limited to usage ofelements from those protocols.

At operation 640, the gNB-CU 106 may precode downlink symbols by thefirst precoding matrix. At operation 645, the gNB-CU 106 may transferthe precoded downlink symbols to the gNB-DU 108. At operation 650, thegNB-CU 106 may transfer one or more elements to the gNB-DU 108.

In some embodiments, the gNB-CU 106 may precode, first symbols from thedata streams by the first precoding matrix to generate second symbolsfor transfer on the H interface to the gNB-DU 108. The gNB-DU 108 mayprecode the second symbols by the second precoding matrix to generatethird symbols for transmission on the antennas. In some embodiments, thegNB-CU 106 may determine the number of virtual ports as a number that isless than the number of antennas coupled to the gNB-DU 108 to cause asize of the second symbols to be less than a size of the third symbols.

In some embodiments, the gNB-DU 108 may determine the second precodingmatrix to convert the second data symbols into third data symbols ofsize based on a number of antennas coupled to the gNB-DU 108. A numberof rows of the second precoding matrix may be equal to the number ofantennas coupled to the gNB-DU 106, and a number of columns of thesecond precoding matrix may be equal to the number of virtual antennaports.

In some embodiments, the first symbols may include a first vector oflength equal to the number of data streams at the gNB-CU 106. The secondsymbols may include a second vector of length equal to the number ofvirtual ports. The second vector may be based on a product of the firstprecoding matrix and the first vector. The third symbols may include athird vector of length equal to the number of antennas coupled. Thethird vector may be based on a product of the second precoding matrixand the second vector.

In some embodiments, the first vector, the second vector, and the thirdvector include symbols for transmission on a resource element (RE) of aplurality of REs during a symbol period of a plurality of symbolperiods.

In some embodiments, if the first symbols are included in a physicaldownlink shared channel (PDSCH), a physical downlink control channel(PDCCH) or demodulation reference signals (DMRSs), the gNB-CU 106 mayprecode, the first symbols by the first precoding matrix for transfer onthe F1 interface to the gNB-DU 108. In some embodiments, if the firstsymbols are included in channel state information reference signals(CSI-RS), a primary synchronization signal (PSS), a secondarysynchronization signal or a physical broadcast channel (PBCH), thegNB-CU 106 may: precode the first symbols by the first precoding matrixfor transfer on the F1 interface to the gNB-DU 108; or transfer thefirst symbols without precoding on the F1 interface to the gNB-DU 108.In some embodiments, the gNB-CU 106 may generate the first symbols basedon a Fourier Transform (FT) operation on the one or more data streams.

At operation 655, the gNB-CU 106 may receive, from the gNB-DU 108,prefiltered uplink symbols from the gNB-DU 108. The gNB-CU 106 maydecode one or more uplink packets based on uplink symbols (including butnot limited to prefiltered uplink symbols) received from the gNB-DU 108.

At operation 660, the gNB-CU 106 may receive one or more elements fromthe gNB-DU 108. The elements may or may not be prefiltered. The elementsmay be related to one or more of: a sounding reference signal (SRS),random access channel (RACH) and/or other.

In some embodiments, an apparatus of a gNB 105 and/or gNB-CU 106 maycomprise memory. The memory may be configurable to store the first andsecond precoding matrixes. The memory may store one or more otherelements and the apparatus may use them for performance of one or moreoperations. The apparatus may include processing circuitry, which mayperform one or more operations (including but not limited tooperation(s) of the method 600 and/or other methods described herein).The processing circuitry may include a baseband processor. The basebandcircuitry and/or the processing circuitry may perform one or moreoperations described herein, including but not limited to determinationof the first and second precoding matrixes. The apparatus may include aninterface to transfer the precoding matrix packet. The interface maytransfer and/or receive other blocks, messages and/or other elements.

In some embodiments, the antennas may be coupled to one or more of: thegNB-DU 108, an apparatus of the gNB-DU 108, the gNB 105, and anapparatus of the gNB 105. In some embodiments, one or more of thefollowing may comprise the antennas: the gNB-DU 108, an apparatus of thegNB-DU 108, the gNB 105, and an apparatus of the gNB 105.

At operation 705, the gNB-DU 108 may receive information related to oneor more signal quality measurements. At operation 707, the gNB-DU 108may transfer, to the gNB-CU 106, information related to the signalquality measurements.

In some embodiments, the gNB-DU 108 may receive the information relatedto the signal quality measurements from the UE 102. In some embodiments,the gNB-DU 108 may transfer information (the information received fromthe UE 102, a portion of the information received from the UE 102,information based on the information received from the UE 102 and/orother) to the gNB-CU 106.

At operation 710, the gNB-DU 108 may receive, from the gNB-CU 106,information related to a second precoding matrix for a downlinkprecoding. At operation 715, the gNB-DU 108 may receive, from the gNB-CU106, information related to a number of virtual antenna ports.

At operation 720, the gNB-DU 108 may determine the second precodingmatrix for the downlink precoding. In some embodiments, the gNB-DU 108may generate, for transmission to the UE 102, a plurality of precodedsignals based on a plurality of candidate precoding matrixes. The gNB-DU108 may receive, from the UE 102, one or more signal qualitymeasurements based on the plurality of precoded signals. The gNB-DU 108may determine the second precoding matrix based at least partly on thesignal quality measurements.

In some embodiments, the gNB-DU 108 may determine the second precodingmatrix. In some embodiments, the information related to the secondprecoding matrix (received from the gNB-CU 106 at operation 710) mayindicate the second precoding matrix. Accordingly, the gNB-DU 108 maynot necessarily perform operation 720, in some embodiments.

At operation 725, the gNB-DU 108 may receive, from the gNB-CU 106,information related to uplink prefiltering. In some embodiments, theinformation may include one or more of: a number of virtual antennaports; information related to the prefiltering matrix (such ascoefficients, size of the matrix and/or other); and/or otherinformation. In some embodiments, the information may be included in aprefiltering matrix packet, although the scope of embodiments is notlimited in this respect.

In some embodiments, the prefiltering matrix may be for conversion offirst symbols received from a UE 102 on a plurality of antennas tosecond symbols for transfer to the gNB-CU 106 on the F1 interface. Insome embodiments, a size of the first symbols may be based on a numberof the antennas, and a size of the second symbols may be based on thenumber of virtual antenna ports. In some embodiments, a number of rowsof the prefiltering matrix may be equal to the number of virtual antennaports, and a number of columns of the prefiltering matrix may be equalto the number of antennas.

At operation 730, the gNB-DU 108 may determine a prefiltering matrix forthe uplink prefiltering. In some embodiments, the gNB-DU 108 maydetermine the prefiltering matrix. For instance, the gNB-DU 108 maydetermine the prefiltering matrix based at least partly on information(such as the number of virtual antenna ports) received at operation 725.In some embodiments, the gNB-CU 106 may determine the prefilteringmatrix and may transfer information that indicates the prefilteringmatrix. Accordingly, the gNB-DU 108 may not necessarily performoperation 730, in some embodiments.

At operation 735, the gNB-DU 108 may receive downlink symbols from thegNB-CU 106. At operation 740, the gNB-DU 108 may precode the downlinksymbols by the second precoding matrix. At operation 745, the gNB-DU 108may transmit the precoded downlink symbols to a UE 102.

In some embodiments, the downlink symbols received from the gNB-CU 106may be prefiltered by the gNB-CU 106 (such as by a first precodingmatrix), although the scope of embodiments is not limited in thisrespect. Accordingly, the symbols transmitted to the UE 102 at operation745 may be precoded by the first and second precoding matrixes, in someembodiments.

At operation 750, the gNB-DU 108 may receive uplink symbols from the UE102. At operation 755, the gNB-DU 108 may prefilter the uplink symbols.At operation 760, the gNB-DU 108 may transfer the prefiltered uplinksymbols to the gNB-CU 106.

In some embodiments, the gNB-DU 108 may prefilter first symbols from theantennas by the prefiltering matrix to generate second symbols fortransfer on the F1 interface to the gNB-CU 106. The gNB-CU 106 maydecode an uplink packet based on the second symbols. In someembodiments, the first symbols may include a first vector of lengthequal to the number of antennas, the second symbols may include a secondvector of length equal to the number of virtual antenna ports, and thesecond vector may be based on a product of the prefiltering matrix andthe first vector.

In some embodiments, the gNB-DU 108 may, if the first symbols areincluded in a physical uplink shared channel (PUSCH) or a physicaluplink control channel (PUCCH): prefilter the first symbols by theprefiltering matrix for transfer on the F1 interface to the gNB-CU 106.In some embodiments, the gNB-DU 108 may, if the first symbols areincluded in a sounding reference signal (SRS) or a random access channel(RACH): prefilter the first symbols by the prefiltering matrix fortransfer on the F1 interface to the gNB-CU 106; or transfer the firstsymbols without prefiltering on the F1 interface to the gNB-CU 106. Insome embodiments, the gNB-DU 108 may generate the first symbols based onan inverse Fourier Transform (FT) operation on signals from theantennas.

In some embodiments, an apparatus of a gNB 105 and/or gNB-DU 108 maycomprise memory. The memory may be configurable to store theprefiltering matrix. The memory may store one or more other elements andthe apparatus may use them for performance of one or more operations.The apparatus may include processing circuitry, which may perform one ormore operations (including but not limited to operation(s) of the method700 and/or other methods described herein). The processing circuitry mayinclude a baseband processor. The baseband circuitry and/or theprocessing circuitry may perform one or more operations describedherein, including but not limited to determination of the prefilteringmatrix. The apparatus may include a transceiver to receive uplink datasymbols from the UE 102. The transceiver may transmit and/or receiveother blocks, messages and/or other element.

At operation 805, the UE 102 may determine one or more signal qualitymeasurements. At operation 810, the UE 102 may transmit informationrelated to the signal quality measurements to the gNB-DU 108. Atoperation 815, the UE 102 may receive, from the gNB-DU 108, downlinksymbols. At operation 820, the UE 102 may transmit, to the gNB-DU 108,uplink symbols.

In some embodiments, an apparatus of a UE 102 may comprise memory. Thememory may be configurable to store the signal quality measurements. Thememory may store one or more other elements and the apparatus may usethem for performance of one or more operations. The apparatus mayinclude processing circuitry, which may perform one or more operations(including but not limited to operation(s) of the method 800 and/orother methods described herein). The processing circuitry may include abaseband processor. The baseband circuitry and/or the processingcircuitry may perform one or more operations described herein, includingbut not limited to determination of the signal quality measurements. Theapparatus may include a transceiver to transmit the information relatedto the signal quality measurements. The transceiver may transmit and/orreceive other blocks, messages and/or other element.

FIG. 9 illustrates example operations in accordance with someembodiments. FIG. 10 illustrates example operations in accordance withsome embodiments. It should be noted that the examples shown in FIGS.9-10 may illustrate some or all of the concepts and techniques describedherein in some cases, but embodiments are not limited by the examples.For instance, embodiments are not limited by the name, number, type,size, ordering, arrangement of elements (such as devices, operations,messages and/or other elements) shown in FIGS. 9-10. Although some ofthe elements shown in the examples of FIGS. 9-10 may be included in a3GPP LTE standard, 5G standard, NR standard and/or other standard,embodiments are not limited to usage of such elements that: are includedin standards.

In some embodiments, a functional split between a central unit (CU) anda distributed unit (DU) may be used. Referring to FIG. 9, three possibleoptions 7-1, 7-2, and 7-3 are shown as (910, 920, 930). For each of theoptions 910, 920, 930, a dotted line is shown. The dotted lines 911,921, 931 correspond to options 910, 920, 930, respectively. For each ofoptions 910, 920, 930, the blocks to the left of the correspondingdotted line may be performed by the CU 106 and the blocks to the rightof the corresponding dotted line may be performed by the DU 108. Forinstance, for option 7-1 (910), the IFFT/CP block 912, DA 913, FFT/CP914, MACH filter 915, AD 916, and analog beamforming 917 are to theright of the line 911. Those functions may be performed by the DU 108.Other blocks to the left of the line, such as precoding 922, resourcemapping 923, prefiltering 924, resource demapping 925 and others to theleft of those blocks may be performed by the CU 106 in option 7-1 (910).In another example, for option 7-2 (920), the blocks 912-917 and 922-925are to the right of the line 921 and may be performed by the DU 108,while other blocks to the left of line 921 may be performed by the CU106.

In some embodiments, a flexible front-haul interface design with aconfigurable function partition between CU 106 and DU 108 for splitphysical layer functionality may be used. In some embodiments, trafficload in the interface, including data and the coefficient, may be fromthe digital antenna port level to user stream level. This may depend onthe capability of the transportation network, in some cases.

In some embodiments, a flexible front-haul design may support unifiedfront-haul interface for physical layer split solution options 7-1 and7-2. A non-limiting example is shown in FIG. 10. In some embodiments,the CU 106 may perform one or more operations included in 1005. In someembodiments, the DU 108 may perform one or more operations included in1010.

The interface format can be unified and configured by CU 106 withdifferent setup, such as number of digital antenna port/data stream,pre-coding and pre-filter coefficients generation and update frequencyaccording to front-haul capability and performance target.

In some embodiments, a pre-filtering block may be used in the uplink.For instance, the pre-filtering may be used after an IFFT and/or FFT. Insome embodiments, a pre-coding block may be used in the downlink. Forinstance, the pre-coding may be performed at the DU 108 before an FFTand/or IFFT. The DU 108 may perform operations related to data size,digital antenna number, data stream number and/or other in accordancewith parameters and/or techniques setup by the CU 106.

In some embodiments, for the downlink, a precoding block may beseparated into two precoding sub-blocks. One precoding operation may beperformed by the CU 106 and the other precoding operation may beperformed by the DU 108. The detail functionality of two sub-blocks maybe controlled by the CU 106, in some embodiments.

In some cases, such an interface design may be flexible to supporttradeoffs between the front-haul interface capability and wirelessperformance with a unified interface controlled by CU 106.

In some cases, one or more of the embodiments described herein mayenable one or more of: a unified interface design for different physicallayer solutions; flexibility to adjust the front-haul traffic from thedigital antenna port level to user stream level according to thetransportation capability without changing the functionality of the DU108; pre-coding and pre-filtering functionality that may be controlledby the CU 106 and may not necessarily need input/intelligence/processingby the DU 108.

In some embodiments, two physical layer split option 7-1 and 7-2 may beunified with the same functionality in DU 108 and CU 106. To make theflexible interface design, more detail on different solutions for uplinkand downlink is given below. For downlink, the traditional precoding maybe separated to two functionalities, precoding 1 and precoding 2, whichmay be loaded in different units in some embodiments. The detailedprecoding solution and coefficient may be generated and controlled bythe CU 106. The precoding matrix can be generated according to differentinformation, such as the CSI feedback (W1 & W2) by UEs 102, SRS basedchannel estimation from UL at CU 106 and/or other. Both the precoding 1and 2 can be wideband, partial band and/or sub-band. The traffic infront-haul interface between two precoding blocks may be various fromuser stream level to digital antenna port level based on the precoding 2final definition and the updating frequency.

In some embodiments, for the uplink, one or more of the following may beused: CP removal, FTT, resource mapping, and/or other. Such operation(s)may be performed to decompose the data and SRS signal. A pre-filteringmay be added at the DU 108 to downsize the data traffic in front-haulinterface. The pre-filtering may be designed as a spatial filteraccording to channel statement information to downsize the receivingdata from digital antenna port level to user stream level. Thecoefficient and updating frequency for pre-filtering will be controlledby CU 106.

In some embodiments, the digital antenna ports may be divided intoseveral groups, and then pre-filtering may be performed within eachgroup. The group number and the number of digital antenna ports pergroup can be configurable, so the virtual antenna port can be adjustedbetween the digital antenna ports and UE stream. This may be a tradeoffbetween system performance and link traffic.

In some embodiments, for uplink and downlink independently, theconfiguration of number of virtual antenna port may be indicated by theCU 106 and capability of maximum number of virtual antenna port in DU108 may be known to CU 106. Then the following example can be used forDL precoding and UL pre-filtering.

In a non-limiting example, for the downlink, suppose the gNB 105 hasN_(TP) transmitting digital antenna ports and serves N_(s) data streamconcurrently. Denote the transmit symbol of stream i as x_(i). The finaltransmission signal over the digital antenna ports with two stepprecoding in frequency domain may be as follows—Y=P₂P₁X. The matrix P₂may be of dimension N_(TP)×N_(VP). The matrix P1 may be a matrix ofdimension N_(VP) x Ns for two steps' precoding individually. The vectorX=[x₁, x₂, . . . , x_(Ns)]^(T) may be original transmit signals. Theparameter N_(VP) may be a number of virtual antenna ports after firststep of precoding. The matrices P₁ and P₂ together may perform the wholedigital beamforming. They may be generated from the feedback CSI, UL SRSbased channel information by various algorithm(s) (including but notlimited to zero-forcing, SVD and/or other) and/or other technique(s).

In some embodiments, the matrices P₁ and P₂ may be different. For PBCH,PDCCH, PSS/SSS and CSI-RS, wideband precoding or DFT based precoding maybe used tor wide coverage according to current discussion in 3GPP.

In some embodiments, for data channel and DMRS, the parameter N_(VP) maybe configurable to adjust the partition between P₁ and P₂. In an idealfront-haul transport network, N_(VP) may be closer to N_(TP). In someembodiments, when N_(VP) is equal to N_(TP), P₂ may be an identitymatrix. This may result in a transparent transmission. All of theprecoding work may be done by the CU 106. When the front-haul transportnetwork is had and/or performs poorly, N_(VP) may be at least N_(s),which means that P₁ may be an identity matrix, and the precoding may beperformed entirely at the DU 108. The precoding coefficients may betransmitted from the CU 106. The granularity and frequency may depend onthe front-haul capability. So the parameter N_(VP) together with amethod to determine P₁ and P₂ may be configurable with the samefunctionality and interface. This may be a compromise among systemperformance, link traffic and implementation complexity, in some cases.

In some embodiments, for the uplink, after resource de-mapping, the SRSsymbol may be decomposed. In some embodiments, the SRS is notpre-filtered. The received PRACH signal may be processed separately, insome embodiments.

In some embodiments, for the data channel, the gNB 105 may includeand/or be coupled to N_(RP) receiving digital antenna ports and mayserve N_(s) data streams concurrently. Denote the corresponding channelfrequency response between stream i and the antenna j element ash_(i,j). The received frequency signal may be written as Y=HX+n. Thematrix H=[h₁, h₂, . . . , h_(Ns)] of size N_(RP) by N_(s) may be achannel response matrix. The vector h_(i)=[h_(i,1), h_(i,2). . . ,h_(i,NRP)]^(T) may be a channel response vector. The vectors X=[x₁, x₂,. . . , X_(Ns)]^(T) and n=[n₁, n₂, . . . , n_(NRP)]^(T) may denoteuplink transmit signals and noise, respectively. The pre-filteringmatrix may be denoted as P_(f) and the pre-filtered data may beY_(prefiltered)=P_(f)Y.

In some embodiments, the antennas may be divided into N_(G) groups,wherein N_(G) can be flexibly configured (such as 1, 2, 4 and/or othervalue). The grouped antenna can be denoted as below.

$H = \begin{bmatrix}H_{{sub}\; 1} \\H_{{sub}\; 2} \\\vdots \\H_{{sub}\; N_{G}}\end{bmatrix}$

In the above, H_(sub i) may include the channel information between allstreams and partial receiving antenna ports. In addition, the digitalantenna ports within each group may have no intersection, in someembodiments, and may be selected independently. Then the pre-filteringmatrix can be expressed as below.

P _(f[N) _(G) _(N) _(S) _(×N) _(RP]) =diag([diag(1/sqrt(diag(H _(sub i)^(H) H _(sub i))))])diag(H ^(H))

A dimension of data that is transferred in front-haul interface may bereduced from N_(RP) to N_(G)*N_(s). For instance, suppose N_(G)=2, andthen the pre-filtering matrix P_(f) can be denoted as below.

$P_{f{\lbrack{2N_{S} \times N_{RP}}\rbrack}} = {\quad{\begin{bmatrix}{{diag}\left( {1/{{sqrt}\left( {{diag}\left( {H_{{sub}\; 1}^{H}H_{{sub}\; 1}} \right)} \right)}} \right)} & 0 \\0 & {{diag}\left( {1/{{sqrt}\left( {{diag}\left( {H_{{sub}\; 2}^{H}H_{{sub}\; 2}} \right)} \right)}} \right)}\end{bmatrix}{\quad\begin{bmatrix}H_{{sub}\; 1}^{H} & 0_{N_{S} \times {N_{RP}/2}} \\0_{N_{S} \times {N_{RP}/2}} & H_{{sub}\; 2}^{H}\end{bmatrix}}}}$

The compressed data stream may be written as below.

Y _(prefiltered[2N) ₃ _(×1]=) P _(f[2N) ₃ _(×N) _(RP) _(]) ×Y

For this case, the dimension of data fed back may be reduced from N_(RP)to 2N_(s). Processing may be based on the prefiltered received data ofsize 2N_(s). In some embodiments, packets for different content andfields in packet header may be used. Non-limiting examples are given inthe table below.

Direction Packet type Packet Content From DU UL Data packet Pre-fitleredPUSCH/PUCCH to CU (UL) SRS packet Pre-filtered or non-pre-filtered SRSRACH packet Pre-filtered or non-pre-filtered PRACH From CU DL Datapacket Precoded PDSCH, PDCCH, DMRS to DU (DL) Control packet Precoded ornon-precoded CSI-RS, SSS/PSS/PBCH Precoding DL precoding coefficient forP2 matrix packet Pre-filtering UL pre-filtering coefficient forpre-filter matrix packet

In some embodiments, field(s) for packet sub type may be used in thepacket header for different content. In some embodiments, for a downlinkdata packet, a field may indicate NVP . In some embodiments, fordownlink precoding, one or more fields may indicate information relatedto one or more of: N_(VP), and N_(TP), P₂ matrix size and/or other.

In some embodiments, for the uplink, N_(VP) may be N_(G)*N_(s). This maybe a dimension after pre-filtering. So for an uplink data packet, afield may indicate N_(VP). For a prefiltering matrix packet, one or morefields may indicate information related to one or more of; N_(VP),N_(RP), a prefiltering matrix size and/or other.

In some embodiments, uplink pre-filtering and/or downlink precoding maybe generated based on one or more of: DFT based beams, a covariancematrix based scheme and/or other. Hence, for a precoding configurationand/or pre-filtering configuration, one or more of the followingelements may be indicated: a precoder/pre-filter generation schemeindicator; a granularity indication, such as one precoder/pre-filter perRB or per Precoding Resource block Group (PRG) or per RB Group (RBG) orper bandwidth part (BWP) or per carrier; a periodicity ofprecoder/pre-filter update; and/or other.

In some embodiments, a packet and/or header related to precoding and/orprefiltering ma include one or more of the following: a granularityindex, such as a carrier index, RB/PRG/RBG/BWP index and/or other; oneor more coefficients of a precoder for a corresponding resource, such asan angle of DFT based beam or coefficient for covariance matrix basedscheme; and/or other.

In some embodiments, for a control packet, few ports will be enabled,and simpler scheme can be used. In some embodiments, the control packetmay include a content indicator for SSS/PSS and PBCH. In someembodiments, for CSI-RS, an independent packet may be used. In someembodiments, the packet may be pre-generated. In some embodiments, thepacket may be transmitted to DU 108 once and saved/transmitted by DU 108on schedule. In some embodiments, the packet may be generated andtransmitted from CU 106 to DU 108.

In some embodiments, a radio access system may include a CU 106 and a DU108. Some functionality between the CU 106 and the DU 108 may be splitinter physical layer. The CU 106 may transmit downlink signals to the DU108 with multiple virtual antenna ports. Partial precoding may beperformed at the DU 108. The CU 106 may receive uplink signals from theDU 106 with virtual antenna ports after pre-filtering at the DU 108.

In some embodiments, a number of virtual antenna ports may be configuredby the CU 106. In some embodiments, the DU 108 may perform a mapping ofthe virtual antenna ports to digital antenna ports by precodingcoefficient(s) transmitted from CU 106. In some embodiments, an angle ofa DFT based precoder or covariance matrix of precoder may be indicatedby CU 106. In some embodiments, a resource granularity of precodingcoefficient(s) can be indicated by CU 106. In some embodiments, aprecoding coefficient update periodicity can be configured by CU 106. Insome embodiments, the DU may perform a mapping of the digital antennaports to virtual antenna ports by pre-filtering coefficient(s)transmitted from CU 106. In some embodiments, a resource granularity ofpre-filtering coefficient(s) may be indicated by CU 106. In someembodiments, a pre-filtering coefficient update periodicity may beconfigured by CU 106.

In some embodiments, an interface between CU 106 and DU 108 may be aunified packet based front-haul interface, covering lower layer splitoption 7-1, 7-2 and other split between these two options. In someembodiments, one or more fields of a packet may indicate one or more of:a content type, such as DL data packet, UL data packet, pre-filteringmatrix packet, precoding matrix packet, control packet for CSI-RS, SSblock and/or other. In some embodiments, one or more fields of thepacket may indicate one or more of: a virtual antenna port number, adigital antenna port number and/or other.

In some embodiments, one or more fields of a packet may indicate one ormore of: a resource granularity, an update periodicity of precodingcoefficient matrix and/or other. In some embodiments, one or more fieldsof a packet may indicate one or more of: a resource granularity, anupdate periodicity of pre-filtering coefficient matrix and/or other.

In Example 1, a generation node B (gNB) may be configured with logicalnodes including a gNB central unit (gNB-CU) and a gNB distributed unit(gNB-DU). The gNB-CU may be configured to communicate with the gNB-DUover an F1 interface. An apparatus of the gNB may comprise memory. Theapparatus may further comprise processing circuitry. The processingcircuitry may be configured to determine, by the gNB-CU, a firstprecoding, matrix and a second precoding matrix for a precoding of oneor more data streams for transmission on a plurality of antennas coupledto the gNB-DU. The precoding may be in accordance with a splitfunctionality between the gNB-CU and the gNB-DU that includes: precodingby the gNB-CU with the first precoding matrix, and precoding by thegNB-DU with the second precoding matrix. The gNB-CU may be configured toprecode first symbols from the data streams by the first precodingmatrix to generate second symbols for transfer on the F1 interface tothe gNB-DU. The gNB-DU may be configured to precode the second symbolsby the second precoding matrix to generate third symbols fortransmission on the antennas. The memory may be configured to store thefirst and second precoding matrixes.

In Example 2, the subject matter of Example 1, wherein the processingcircuitry may be further configured to, by the gNB-CU, encode aprecoding matrix packet that indicates the second precoding matrix, theprecoding matrix packet encoded for transfer to the gNB-DU on the F1interface.

In Example 3, the subject matter of one or any combination of Examples1-2, wherein: a number of rows of the first precoding matrix may beequal to a configurable number of virtual ports, a number of columns ofthe first precoding matrix may be equal to a number of the data streams,a number of rows of the second precoding matrix may be equal to a numberof the antennas, and a number of columns of the second precoding matrixmay be equal to the number of virtual ports.

In Example 4, the subject matter of one or any combination of Examples1-3, wherein the first symbols may include a first vector of lengthequal to the number of data streams. The second symbols may include asecond vector of length equal to the number of virtual ports. The secondvector may be based on a product of the first precoding matrix and thefirst vector. The third symbols may include a third vector of lengthequal to the number of antennas. The third vector may be based on aproduct of the second precoding matrix and the second vector.

In Example 5, the subject matter of one or any combination of Examples1-4, wherein the first vector, the second vector, and the third vectormay include symbols for transmission on a resource element (RE) of aplurality of REs during a symbol period of a plurality of symbolperiods.

In Example 6, the subject matter of one or any combination of Examples1-5, wherein the processing circuitry may be further configured to, bythe gNB-CU, determine the number of virtual ports as a number that isless than the number of antennas to cause a size of the second symbolsto be less than a size of the third symbols.

In Example 7, the subject matter of one or any combination of Examples1-6, wherein the processing circuitry may be further configured to, bythe gNB-CU, if the first symbols are included in a physical downlinkshared channel (PDSCH), a physical downlink control channel (PDCCH) ordemodulation reference signals (DMRSs): precode the first symbols by thefirst precoding matrix for transfer on the F1 interface to the gNB-DU.

In Example 8, the subject matter of one or any combination of Examples1-7, wherein the processing circuitry may be further configured to, bythe gNB-CU, if the first symbols are included in channel stateinformation reference signals (CSI-RS), a primary synchronization signal(PSS), a secondary synchronization signal or a physical broadcastchannel (PBCH): precode the first symbols by the first precoding matrixfor transfer on the Ft interface to the gNB-DU; or transfer the firstsymbols without precoding on the F1 interface to the gNB-DU.

In Example 9, the subject matter of one or any combination of Examples1-8, wherein the processing circuitry may be further configured to, bythe gNB-CU, generate the first symbols based on a Fourier Transform (FT)operation on the one or more data streams.

In Example 10, the subject matter of one or any combination of Examples1-9, wherein the processing circuitry may be further configured to, bythe gNB-DU, decode a signal quality measurement from a User Equipment(UE). The processing circuitry may be further configured to, by thegNB-CU, based at least partly on the signal quality measurement: selectthe first precoding matrix from first candidate precoding matrixes; orselect the second precoding matrix from second candidate precodingmatrixes.

In Example 11, the subject matter of one or any combination of Examples1-10, wherein the apparatus may further include a transceiver totransmit the third symbols.

In Example 12, the subject matter of one or any combination of Examples1-11, wherein the apparatus may further include the antennas.

In Example 13, the subject matter of one or any combination of Examples1-12, wherein the processing circuitry may include a baseband processorto determine the first and second precoding matrixes.

In Example 14, a generation Node-B (gNB) may be configured with logicalnodes including a gNB central unit (gNB-CU) and a gNB distributed unit(gNB-DU), the gNB-CU configured to communicate with the gNB-DU over anF1 interface. A non-transitory computer-readable storage medium maystore instructions for execution by one or more processors to performoperations for communication by the gNB. The operations may configurethe one or more processors to, by the gNB-CU: precode, by a firstprecoding matrix, first data symbols from one or more data streams togenerate second data symbols for transfer to the gNB-DU on the F1interface. A size of the second data symbols may be based on aconfigurable number of virtual antenna ports. The operations may furtherconfigure the one or more processors to, by the gNB-CU, encode aprecoding matrix packet for transfer to the gNB-DU on the F1 interface.The precoding matrix packet may indicate the number of virtual antennaports. The operations may further configure the one or more processorsto, by the gNB-DU, determine a second precoding matrix to convert thesecond data symbols into third data symbols of size based on a number ofantennas coupled to the gNB-DU. A number of rows of the second precodingmatrix may be equal to the number of antennas coupled to the gNB-DU. Anumber of columns of the second precoding matrix may be equal to thenumber of virtual antenna ports.

In Example 15, the subject matter of Example 14, wherein the operationsmay further configure the one or more processors to, by the gNB-DU:generate, for transmission to a User Equipment (UE), a plurality ofprecoded signals based on a plurality of candidate precoding matrixes;decode, from the UE, one or more signal quality measurements based onthe plurality of precoded signals; and determine the second precodingmatrix based on the signal quality measurements.

In Example 16, a generation node B (gNB) may be configured with logicalnodes including a gNB central unit (gNB-CU) and a gNB distributed unit(gNB-DU). The gNB-CU may be configured to communicate with the gNB-DUover an F1 interface. An apparatus of the gNB may comprise memory. Theapparatus may further comprise processing circuitry. The processingcircuitry may be configured to, by the gNB-DU: decode, from the gNB-CU,a prefiltering matrix packet that indicates a number of virtual antennaports. The processing circuitry may be further configured to, by thegNB-DU: determine a prefiltering matrix to convert first symbolsreceived from a User Equipment (UE) on a plurality of antennas to secondsymbols for transfer to the gNB-CU on the F1 interface. A size of thefirst symbols may be based on a number of the antennas, and a size ofthe second symbols may be based on the number of virtual antenna ports.A number of rows of the prefiltering matrix may be equal to the numberof virtual antenna ports, and a number of columns of the prefilteringmatrix may be equal to the number of antennas. The memory may beconfigured to store the prefiltering matrix.

In Example 17, the subject matter of Example 16, wherein the processingcircuitry may be further configured to, by the gNB-DU, prefilter firstsymbols from the antennas by the prefiltering matrix to generate secondsymbols for transfer on the Ft interface to the gNB-CU. The processingcircuitry may be further configured to, by the gNB-CU, decode an uplinkpacket based on the second symbols.

In Example 18, the subject matter of one or any combination of Examples16-17, wherein the first symbols may include a first vector of lengthequal to the number of antennas. The second symbols may include a secondvector of length equal to the number of virtual antenna ports. Thesecond vector may be based on a product of the prefiltering matrix andthe first vector.

In Example 19, the subject matter of one or any combination of Examples16-18, wherein the processing circuitry may be further configured to, bythe gNB-CU, select the number of virtual antenna ports as less than thenumber of antennas to cause a size of the second symbols to be less thana size of the first symbols.

In Example 20, the subject matter of one or any combination of Examples16-19, wherein the processing circuitry may be further configured to, bythe gNB-DU, if the first symbols are included in a physical uplinkshared channel (PUTSCH) or a physical uplink control channel (PUCCH):prefilter the first symbols by the prefiltering matrix for transfer onthe F1 interface to the gNB-CU.

In Example 21, the subject matter of one or any combination of Examples16-20, wherein the processing circuitry may be further configured to, bythe gNB-DU, if the first symbols are included in a sounding referencesignal (SRS) or a random access channel (RACH): prefilter the firstsymbols by the prefiltering matrix for transfer on the F1 interface tothe gNB-CU; or transfer the first symbols without prefiltering on the F1interface to the gNB-CU.

In Example 22, the subject matter of one or any combination of Examples16-21, wherein the processing circuitry may be further configured to, bythe gNB-DU, generate the first symbols based on an inverse FourierTransform (FT) operation on signals from the antennas.

In Example 23, the subject matter of one or any combination of Examples16-22, wherein the processing circuitry may be further configured to, bythe gNB-DU, decode a signal quality measurement from the UE. Theprocessing circuitry may be further configured to, by the gNB-CU, selectthe prefiltering matrix from candidate prefiltering matrixes based atleast partly on the signal quality measurement.

In Example 24, a generation Node-B (gNB) may be configured with logicalnodes including a gNB central unit (gNB-CU) and a gNB distributed unit(gNB-DU). The gNB-CU may be configured to communicate with the gNB-DUover an F1 interface. An apparatus of the gNB may comprise means for, bythe gNB-CU: precoding, by a first precoding matrix, first data symbolsfrom one or more data streams to generate second data symbols fortransfer to the gNB-DU on the F1 interface. A size of the second datasymbols may be based on a configurable number of virtual antenna ports.The apparatus may further comprise means for, by the gNB-CU, encoding aprecoding matrix packet for transfer to the gNB-DU on the F1 interface,wherein the precoding matrix packet indicates the number of virtualantenna ports. The apparatus may further comprise means for, by thegNB-DU, determining, a second precoding matrix to convert the seconddata symbols into third data symbols of size based on a number ofantennas coupled to the gNB-DU. A number of rows of the second precodingmatrix may be equal to the number of antennas coupled to the gNB-DU. Anumber of columns of the second precoding matrix may be equal to thenumber of virtual antenna ports.

In Example 25, the subject matter of Example 24, wherein the apparatusmay further comprise means for, by the gNB-DU: generating, fortransmission to a User Equipment (LTE), a plurality of precoded signalsbased on a plurality of candidate precoding matrixes; decoding, from theUE, one or more signal quality measurements based on the plurality ofprecoded signals; and determining the second precoding matrix based onthe signal quality measurements.

The Abstract is provided to comply with 37 C.F.R. Section 1.72(b)requiring an abstract that will allow the reader to ascertain the natureand gist of the technical disclosure. It is submitted with theunderstanding that it will not be used to limit or interpret the scopeor meaning of the claims. The following claims are hereby incorporatedinto the detailed description, with each claim standing on its own as aseparate embodiment.

1-23. (canceled)
 24. A base station comprising: a central unit (CU) anda distributed unit (DU) coupled by an interface; wherein the DU iscoupled to a plurality of antennas, wherein the CU is configured toreceive signal quality information from the DU via the interface,wherein the signal quality information is related to one or more signalquality measurements.
 25. The base station of claim 24, wherein theantennas are configured to receive an uplink signal from a userequipment (UE) device, wherein the DU is configured to decode the one ormore signal quality measurements from the uplink signal.
 26. The basestation of claim 24, wherein the DU is configured to receive a soundingreference signal (SRS) from an uplink signal, and provide the SRS to theCU through the interface.
 27. The base station of claim 24, wherein theDU is configured to receive a random access channel (RACH) from anuplink signal, and provide the RACH to the CU through the interface. 28.The base station of claim 24, wherein physical layer processing of thebase station is split between the CU and DU.
 29. The base station ofclaim 24, wherein the DU is configured to pre-filter antenna-specificcomponents of an uplink signal, and transfer symbols of the pre-filteredsignal to the CU via the interface.
 30. The base station of claim 24,wherein a first of the one or more signal quality measurements isreceived signal power or average received signal power.
 31. The basestation of claim 24, wherein a first of the one or more signal qualitymeasurements is signal-to-noise ratio (SNR) or reference signal receivedpower (RSRP).
 32. The base station of claim 24, wherein a first of theone or more signal quality measurements is reference signal receivedquality (RSRQ) or received signal strength indicator (RSSI).
 33. Thebase station of claim 24, wherein the CU and DU are not co-located. 34.The base station of claim 24, wherein the CU is configured to determinea first precoding matrix and a second precoding matrix for precoding atransmission of one or more downlink data streams via the plurality ofantennas, wherein the CU is configured to apply a first portion of theprecoding using the first precoding matrix, wherein the DU is configuredto apply a second portion of the precoding using the second precodingmatrix.
 35. A method for operating a base station, the methodcomprising: sending signal quality information from a distributed unit(DU) of the base station to a central unit (CU) of the base station,wherein the DU is coupled to a plurality of antennas, wherein the signalquality information is related to one or more signal qualitymeasurements.
 36. The method of claim 35, further comprising: receiving,at the DU, an uplink signal from a user equipment (UE) device; anddecoding, at the DU, the one or more signal quality measurements fromthe uplink signal.
 37. The method of claim 35, wherein a first of theone or more signal quality measurements is one of the following:received signal power, average received signal power, signal-to-noiseratio (SNR), reference signal received power (RSRP), reference signalreceived quality (RSRQ), received signal strength indicator (RSSI). 38.The method of claim 35, further comprising: receiving, at the DU, asounding reference signal (SRS) from an uplink signal; and providing theSRS to the CU.
 39. The method of claim 35, further comprising: receivinga random access channel (RACH) from an uplink signal, and providing theRACH to the CU.
 40. The method of claim 35, wherein physical layerprocessing of the base station is split between the CU and DU.
 41. Themethod of claim 35, further comprising: pre-filtering, at the DU,antenna-specific components of an uplink signal; and transferringsymbols of the pre-filtered signal to the CU.
 42. The method of claim36, wherein the CU and DU are not co-located, wherein the base stationis a next generation Node B of 3GPP 5G NR.
 43. A non-transitory memorymedium storing program instructions, wherein the program instructions,when executed by one or more processors, cause the one or moreprocessors to: send signal quality information from a distributed unit(DU) of a base station to a central unit (CU) of the base station,wherein the DU is coupled to a plurality of antennas, wherein the signalquality information is related to one or more signal qualitymeasurements.